Gunn-Hilsum Effect in Mechanically Strained Silicon Nanowires: Tunable Negative Differential Resistance

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• The Gunn (or Gunn-Hilsum) Effect, characterized by negative differential resistivity (NDR), arises from electron transfer between energy subbands.
• This effect is observed in semiconductors like GaAs but is typically absent in bulk silicon due to large energy spacing.

Purpose of the Study:

• To investigate the induction of the Gunn Effect and NDR in silicon nanowires (SiNWs).
• To explore the influence of strain on NDR onset and resistivity modulation in SiNWs.

Main Methods:

• Density Functional Theory (DFT)
• Semi-empirical 10 orbital (sp3d5s*) Tight Binding method
• Ensemble Monte Carlo (EMC) simulations

Main Results:

• Gunn Effect and NDR were successfully induced in 3.1 nm diameter SiNWs under +3% strain and 5000 V/cm electric field.
• The onset of NDR in I-V characteristics was found to be reversibly adjustable by applied strain.
• Strain modulated resistivity by a factor of 2.3 in SiNWs without intrinsic NDR.

Conclusions:

• Strain engineering offers a novel pathway to induce and control the Gunn Effect and NDR in SiNWs.
• These findings present promising opportunities for SiNWs in advanced applications like electromechanical sensors and tunable microwave oscillators.